“Brakes” light constantly on in instrument cluster

Fabrice · Jun 22, 2022

@71ProjectJunk
I use a large flat screwdriver alone, as you do not need any real tension when you take a certain order and have the tensioner almost loose, but the last one that connects to top needs to glide like 1 inch over the screwdriver while tension builds up before it flips behind and locks...
When I was young, all went in every time in one try without even thinking,
but now... maaaan do I swear every time I need service these things!!

I really need to buy one of these pliers kit. Affordable too. Thanks for the reminder!

jscott · Oct 10, 2024

Hey, pulled up this old thread so I did not have to start another one. Getting my car ready to take to a show on Sat, fired it up for the first time in about 6 weeks. Breaks light is on, fluid was low, about 1/2 full. There are no leaks, all new break lines 2 years ago, only about 500 miles on since. From reading this thread perhaps some air in line or a bad valve? Car is going into my shop next month for some work so will have it looked at thenm, but is it ok to drive now??? I could not take it for a test drive tonight as I have some construction material in the driveway but will do so tomorrow.

MikeGriese · Oct 10, 2024

If there is less brake fluid in it now, it had to go somewhere. Brake fluid will evaporate, so you would need to look pretty close to see if there is any residue or dirt rings left by the fluid. Or you could have had some air that somehow, magically, found it's way out of the calipers or slave cylinders all the way through the brake lines to bubble up in the master cylinder. Not likely. Refill the reservoir and bleed the brakes if you can.

jscott · Oct 11, 2024

It will have to wait for a shop to do that. Question still stands, can I drive it?

MikeGriese · Oct 11, 2024

How far do you need to go? How long did it take for the reservoir to run low? What do you hit if you pull out of the garage and the brakes don't work? Top off the brake fluid whatever you do.

jscott · Oct 11, 2024

I am ashamed to admit it but I have not opened the reservoir to check in 2 years until yesterday when the light came on. Have about 40 miles each way so I will keep an eye on it. Will take a short test drive today as well.

ROCKET70 · Oct 11, 2024

It could be leaking out the back of the master cylinder. The weirdest one I ever had was leaking through the casting of the master cylinder it was so porous.
I just had to change the master cylinders on my 2 Oldsmobiles they were leaking out the back. I know their GM and that's why.

basstrix · Oct 11, 2024

jscott said:
I am ashamed to admit it but I have not opened the reservoir to check in 2 years until yesterday when the light came on. Have about 40 miles each way so I will keep an eye on it. Will take a short test drive today as well.

With the fluid low, you have a leak somewhere (assuming low miles on the brake pads and shoes). If you're not finding any signs of fluid at the wheels it must be somewhere else. Take a look at the Combo Valve on the driver's side fender apron. It could also be leaking into the brake booster from rear of master cylinder.

1. You said it was about 1/2 full. There are 2 reservoirs....were they both down an equal amount? If only one, which one? The large goes to front and small to rear.

2. How does the pedal feel when you pump it? Does it hold steady? If there's a leak, it will slowly sink to the floor...or it could be really bad, and sink rapidly.

I have driven many vehicles with failing master cylinders far enough to get the from a customer's house to the shop w/o having to tow. It's a judgement call and if you've never done it, I'd say don't try it.

jscott · Oct 11, 2024

both were at the same level. Pedel feels good, not spongy and not low, feels like it always has. I see no fluid coming from the valve at all, nor at any of the wheels.

basstrix · Oct 11, 2024

jscott said:
both were at the same level. Pedel feels good, not spongy and not low, feels like it always has. I see no fluid coming from the valve at all, nor at any of the wheels.

If the pedal feels good, you're probably ok, but I would carefully drive it somewhere low-risk where you can test the brakes.

The fluid level will drop as the pads and shoes wear....it's possible that's what you're observing. However, the brake light being on, indicates something is awry.

jscott · Oct 11, 2024

Upon deeper inspection it looks like a small leak at the back of the reservoir where it meets the boost as there is paint loss at the bottom front of the booster. Guess never checking the fluid level for 2 gears has taken its toll. No excuses!

jscott · Oct 12, 2024

Well drove 100 miles roundtrip to /from show with no issues. Will have all addressed when it goes into the shop next month. I guess no one at the show (Roswell Motor Festival) knew of the problem as she was named Best of Show.

“Brakes” light constantly on in instrument cluster

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